Acquisition of a modern state-of-the art analytical ultracentrifuge (AUC) by the University Of Washington School Of Medicine is sought. Analytical ultracentrifugation is a powerful technique to characterize the size, shape, and oligomerization state of proteins and their binding of ligands ranging from ions to other biomacromolecules. The requested instrument will serve the NIH-supported research projects of six Major Users, six Minor Users, and other users on a more infrequent basis. Since the decommissioning of a Model E centrifuge in 1988, researchers at UW have had to collect AUC data either in collaboration with another group off-site or at fee-for- service facilities. Neither of these models is efficient and the latter is extremely costly. The identified user group includes members of five basic science departments within the School of Medicine and a member at the associated Fred Hutchinson Cancer Research Center. The NIH-supported research that will be enhanced by the requested instrument represents a wide spectrum of human health and disease, including numerous infectious diseases and cancer.